Field of the Invention
The present invention relates to an organic light emitting display device and a method of manufacturing the same.
Discussion of the Related Art
With the advancement of information-oriented society, various requirements for display devices for displaying an image are increasing. Therefore, various display devices such as liquid crystal display (LCD) devices, plasma display panel (PDP) devices, organic light emitting display devices, etc. are being used recently.
As a type of display device, organic light emitting diode (OLED) display devices are self-emitting display devices and are better in viewing angle and contrast ratio than LCD devices. Also, since the organic light emitting display devices do not need a separate backlight, it is possible to lighten and thin the organic light emitting display devices, and the organic light emitting display devices are excellent in power consumption. Furthermore, the organic light emitting display devices are driven with a low direct current (DC) voltage, have a fast response time, and are low in manufacturing cost.
The organic light emitting display devices each include a display panel that displays an image. The display panel includes a plurality of organic light emitting devices and a bank that divides adjacent organic light emitting devices. The organic light emitting devices each includes a first electrode, a hole transporting layer, an organic light emitting layer, and an electron transporting layer, and a second electrode. In this case, when a high-level voltage is applied to the first electrode and a low-level voltage is applied to the second electrode, a hole and an electron respectively move to the organic light emitting layer through the hole transporting layer and the electron transporting layer and are recombine in the organic light emitting layer to emit light.
Organic light emitting display devices may be divided into a top emission type and a bottom emission type. The top emission type is a type where light emitted from an organic light emitting device is output in a direction toward an upper substrate of a display panel that does not include the TFTs for driving the OLEDs, and the bottom emission type is a type where the light emitted from the organic light emitting device is output in a direction toward a lower substrate of the display panel that includes the TFTs for driving the OLEDs.
In the top emission type, since the light emitted from the organic light emitting device is output in the direction toward the upper substrate of the display panel that does not include the TFTs for driving the OLEDs, an opening area is wide. Also, in the top emission type, since it is not required to design thin film transistors (TFTs) in consideration of the opening area, an area occupied by the TFTs is wide.
However, even in a top emission type OLED display, when the light emitted from the organic light emitting device travels in a direction toward a bank dividing the organic light emitting device, instead of the direction toward the upper substrate, the light can be lost without being irradiated in the direction toward the upper substrate. If a loss of the light emitted from the organic light emitting device is reduced, a lifetime of the organic light emitting device increases, and moreover, consumption power of the organic light emitting display device is reduced.